I have seen the insides of more hospitals than I care to remember. In the process, I have been deeply impressed by the quality of the care received, but I have also become increasingly nervous about the potential health impacts of being in hospital, firstly because of news reports about the growing prevalence of MRSA, and now I am also concerned about the prevalence of toxic chemicals on hospital wards, thanks to Gary Cohen and his organisation Health Care Without Harm.

Cohen's healthier hospitals initiative sets out to reduce the use of these poisons in our hospitals.

The recent controversy about the danger to honeybees from a widely used class of pesticides, the neonicitinoids is comparable. The chemical industry has a history of denying such effects, from the Silent Spring onwards. The industry, Cohen told me, "continues to build a fortress around the argument that low dose exposures to toxic chemicals do not matter." So a core objective for Health Care Without Harm has been to mobilise the healthcare sector's purchasing power to pressure chemical companies to change.

When I asked what one thing Cohen wished he had known years ago, he offered two answers. The first was that he wished he had realised how much more effective it would have been to "have couched our rhetoric and pitch within the framework of healthcare quality and safety from the beginning." And the second? It would have been an immense help, he said, to have known how to make the business case from the outset. "We did this on our early issues, for example mercury measuring devices and medical waste, but appealing to the bottom line benefits in addition to our mission would have accelerated progress sooner."

That approach is now central to the Healthier Hospitals Initiative, announced earlier this month. The initiative represents over 500 hospitals across the United States, or 10% of the national hospital market. Together, participants marshal more than $20bn in purchasing power. And the aim is to recruit an additional 1,500 hospitals over the next three years, or 40% of US hospitals. Six challenges are spotlighted: engaged leadership, safer chemicals, leaner energy, less waste, healthier food and smarter purchasing. The new website contains "how to" guides, complete with the relevant business cases.

One system change issue the initiative faces involves lobbying the US Internal Revenue Service (IRS) to change its community benefit reporting for non-profit hospitals, to allow them to spend community benefit money for programmes that would improve the environmental health of the communities they service. If successful, Cohen says this move alone "would potentially unlock hundreds of millions of dollars nationwide for hospitals to support efforts to reduce environmental exposures in their communities, educate patients and employees about climate change and public health, and support local and sustainable agriculture in their communities."

One champion of the Healthier Hospitals Initiative is Knox Singleton, CEO of Inova Health System in Falls Church, Virginia. "Hospitals can no longer afford to be out of sync in their day-to-day work of healing and treating and the environmental impact they have in communities across the country," he said. "By reducing waste and conserving energy, among other challenges, we can not only reduce operational costs, but we can improve the health of people in our communities before they ever enter a hospital."

Interestingly, a new report just released by the Health Care Without Harm/Healthier Hospitals Initiative Research Collaborative is titled Creating a Culture of Sustainability. Among key findings: by creating an environmentally preferable purchasing programme, nationwide health care provider Kaiser Permanente estimates that it will save $26m a year.

Something that has interested me for a while is the way in which our cultures constrain or open out the potential for critical behavioural changes, and Kaiser Permanente comes up time and again as a leader in this space. I asked Cohen why he thinks that is? "Because they not only run hospitals but also insure people," he replied, "so their business model tilts them toward the prevention of chronic diseases, to avoid having to pay all the treatment and insurance costs for their members. Sustainability and disease prevention are aligned with their core business model. That is not the case with other systems that reward treatment rather then outcomes. We can only transform healthcare if it pays to keep people healthy. And the environment is critical to people's health."

So what big changes does Cohen see in the way the sector's bottom line is measured by 2022? The first thing, he replies, is that "reductions in greenhouse gases will be measured in health costs avoided to treat asthma and other diseases related to climate change." Second, the coming "transformations in the healthcare food supply chain and community programs will be measured in reductions in obesity and diabetes." And third, "the transformation in the chemicals supply chain will be factoring in reductions in lost work time and reduced workers' compensation claims, plus broader reductions in cancer, learning disabilities, Parkinson's disease and other chronic diseases that threaten to topple the whole healthcare system."

At a time when there is growing interest in changing behaviours, cultures and systems, it will be well worth keeping close tabs on the progress of Health Care Without Harm and the Healthier Hospitals Initiative. Apart from anything else, I'd like to know where to ask the ambulance to go next time.